German Research Institution Using SPOT Trace to Conduct Worldwide Oceanography Research

Hereon has designed and engineered innovative ocean drifter devices built around SPOT Trace which monitor ocean surface currents and reveal how biodiversity levels change in the world’s major rivers and seas. “Our purpose is to understand in greater detail the surface flow of water and organisms around the globe,” explains Dr. Jochen Horstmann, scientist at Hereon.

“We already have a reasonable idea of how currents work from satellite imagery and numerical models. However, we need reliable measurements of surface currents to better understand their processes and to improve our models,” he adds. The researchers use surface floats, or drifters, fitted with an underwater sail suspended at about half a metre depth. These drifters report their position every five minutes and therefore track the near-surface currents, which are heavily influenced by gales, storms and waves.

“As researchers, we always strive to get best possible value for money in the equipment we use, not only for us but for those governments, institutions and private individuals who fund our work.” he says. “We needed drifters that were economical, but when we looked at what devices were already available, these were typically very expensive, so we decided to build drifters ourselves,” he adds.

Horstmann and his colleagues knew they needed to build drifters capable of capturing and transmitting data even in extreme ocean conditions. “Our drifter needed to be robust enough to endure the elements, in particular severe wind conditions and waves,” explains Horstmann.

Position information is transmitted via the Globalstar satellite fleet in Low-Earth Orbit (LEO). “By looking at the data transmitted by the SPOT Trace-equipped drifters, we can see where water and the organisms being carried flow and how biodiversity is affected,” he adds.

Hereon is also collaborating with the EU-funded Atlanteco project. Dr. Paulo Calil, a fellow scientist with Hereon, explains the Microbiomes experiment, which is the focus of Atlanteco. 

Marine micro-organisms play an essential role in the ocean ecosystem, representing more than two-thirds of marine biomass. They are the first link in an immense food chain, feeding a good part of humanity; they also capture atmospheric carbon dioxide and deliver half of the oxygen we breathe every day. 

“Over a billion microorganisms live in every litre of seawater, and thanks to plankton, the ocean absorbs 25% of the CO2 emitted by humans,” explains Dr. Calil. “But while an essential cog in the great climate machine, the functioning of this microbial world remains largely unknown,” he says.

“Our oceans are changing: They are becoming hotter on the surface, because of climate change, and the oceans are becoming more stratified,” Dr Calil explains.

Changes in ocean currents affect transport and connectivity patterns. These studies are helping researchers to understand the role of currents in the oceans’ biodiversity, and reveal the locations where biodiversity is intensifying. “They show how currents interact with plankton. Currents transport nutrients, they mix the ocean, bringing these nutrients to the surface and redistributing them horizontally, igniting surface phytoplankton blooms, “says Dr. Calil.

“There are widespread consequences of changes in currents for marine productivity, which in turn affects carbon levels and the whole ‘machinery’ of the ocean can be affected, as can weather patterns in coastal regions,” he adds. Additionally, many parts of the ocean where the organisms are travelling are very important economically for fisheries, he shares.

Hereon’s drifters equipped with SPOT Trace have shown that the organisms travel extremely far, due to intensifying currents. For example, in the South Atlantic, swirling eddies that form on the southern tip of Africa are seen to spread species all the way to eastern South America.

SPOT Trace’s energy-efficient devices are playing a crucial role here: “Even after 150 days in the ocean, the drifters continue to send data, despite being subject to some rough conditions, waves and strong winds – we’re delighted and really impressed with SPOT Trace,” comments Horstmann.

Plankton (which literally means ‘drifter’) are carried by the currents, and these disperse genes, leading to biodiversity. The researchers are exploring how different species interact with the water flows.

Physical oceanographers, microbiologists, biologists, geneticists, and biological oceanographers are all participating and benefitting from these research endeavours.

Article By: Gavan Murphy